• Dial *004*3141234567*11#
  • Press Send
  • You will receive a message stating unanswered calls are being forwarded for voicemail.
  • 11 is voice, 25 is data, 13 is fax.
  • If you don't type *11# you will receive a message stating all calls (for the previous conditions) are being forwarded
  • #004# to reset forwarding options.
  • To adjust the number of seconds until the call is forwarded to voicemail *004*3141234567*11*24#  24 seconds in this case.  Each ring is 6 seconds.

3141234567 is is the 10 digit number you'll use, such as your Google Voice number.  You can use an old phone like an iPhone 5 with your new sim from an iPhone 8, XR, etc to forward the calls if it doesn't work on your newer phone, then place your sim back in your phone.  This is supposedly no longer supported by new phones and apparently Google Voice, but this is a way around that issue.